In a nutshell, it’s about semantics, timing and eligibility.
The dose per se is exactly the same. The difference is who gets it, why and when.
For those who did not have a good immune response to the vaccine (both doses of Pfizer and Moderna or one dose of the J&J), it is considered a third dose. For everyone else, in whom immune protection starts to wane a bit, it is a booster. At this stage, only the Pfizer vaccine is approved for a third dose. Moderna is surely going to get approval soon and eventually, so will J&J.
If your immune system is not responding the way it should in some way, you may not respond to the vaccine regimen as well. Some estimates are that, for example if you are on anti-rejection drugs for an organ transplant, you may only get a 30% response after the second mRNA vaccine dose. Adding a third dose, increases response to over 50%. Still not as good as what a healthy immune system would provide (95% for the original virus and 60-75% for Delta), but it is still very good. Significantly better than the typical flu vaccine.
We have heard a lot about “at risk” individuals as well as people who are “immunocompromised”. There are some obvious people at risk such as those as mentioned above, on medications which intentionally reduce our immune systems ability to respond properly. This includes anyone taking medication for inflammation such as arthritis or for other autoimmune conditions such as psoriasis, multiple sclerosis, asthma, ulcerative colitis and crohn’s or thyroid disease. These include steroids and immune modulators which are heavily advertised on TV. Drugs to treat cancer often impact our immune system because they typically target rapidly reproducing cells, which is why these drugs also cause anemia and lower platelet (clotting cells) numbers.
Some less obvious things which will impact on your immune system are even over-the-counter drugs like Advil (ibuprofen), Relafen or Aleve. The most commonly purchased drugs in American pharmacies are antacids and they also impact on immune function. H2R (Histamine 2 Receptor) blockers, like Zantac and Pepcid, and the much stronger PPIs (Proton Pump Inhibitors), like Nexium and Prevacid, indirectly affect the immune system by enabling enhanced bacterial growth in the stomach and small intestine. This leads to inflammation and malabsorption not to mention impacting on the gut immune function directly. 70% of our immune function comes from the gut. They are NOT good to take regularly. Treat the cause of reflux, overeating and bad diet, not the symptoms.
Some conditions, by their very nature, impact on our immune system. HIV is the classic immune destroying disease. A common, less recognized one is diabetes, which affects at least 30% of Americans. Another 50% are estimated to be insulin resistant, the precursor to diabetes. This also impacts your immune system. Anyone who has had cancer in the past is considered immunocompromised. Cardiovascular/Atherosclerotic disease causes inflammation, overstimulation of the immune system, and impairs blood flow, not only to the obvious organs like the heart, extremities, penis (ED is the “canary in the coalmine” when is comes to heart disease), brain and lungs, but also the bone marrow where our immune cells originate. Even obesity itself impairs immune function. The number one condition associated with people admitted to ICUs with Covid-19 remains obesity. Unfortunately, obesity rates continue to rise with almost 43% of Americans being obese, including 20% of those under 20 years old. We have yet to determine how much obesity rates have increased during the pandemic.
Obviously kids under 12, who are not able to get vaccination, are at risk. Really young kids have incompletely developed immune systems. However, babies born to mothers who are vaccinated, including while pregnant, have a leg up as those antibodies pass through the placenta, protecting the baby after delivery.
Older people are at risk because their immune system becomes less efficient with age, not to mention the accumulation of diseases like hypertension, weight gain and inactivity, a immunosuppressant by itself.
Given all that, you could argue that practically everyone is immunosuppressed and is at an increased risk, and you would be correct. We are a fat (most obese in the world) and sick (one of the highet chronic disease rates) population which makes it not surprising that we account for 20% of the Covid infections and deaths worldwide, despite only having 4% of the population.
Should everyone get a third dose? As soon as possible. Studies clearly show that boosting the immune response to the SARS-Cov-2 virus provides significant protection from getting sick and certainly from having a severe case of Covid. For now, we need the really immunocompromised people to get vaccinated first. For them, we are calling it the third dose, since the first two were not adequate to begin with. Cancer, immune modulating medications, HIV… We also need to vaccinate those in the eye of the storm. The healthcare and firstline workers caring for the sick.
But we also need to encourage those who have not gotten any vaccines to get vaccinated. It is the caring thing to do. Whatever you feel about your own health is your business but we all should be looking out for everyone else and vaccination is the key to getting through and dealing with this disease.
Stay safe and be well.